Drought is one of the major constraints in wheat production and causes a huge loss at grain-filling stage. In this study we highlighted the response of different wheat genotypes under drought stress at the grain-filling stage. Field experiments were conducted to evaluate 72 wheat (Triticum aestivum L.) genotypes under two water regimes: irrigated and drought condition. Four wheat genotypes, two each of drought tolerant (IC36761A, IC128335) and drought-susceptible category (IC335732 and IC138852) were selected on the basis of agronomic traits and drought susceptibility index (DSI), to understand their morphological, biochemical and molecular basis of drought stress tolerance. Among agronomic traits, productive tillers followed by biomass had high percent reduction under drought stress, thus drought stress had a great impact. Antioxidant activity (AO), total phenolic and proline content were found to be significantly higher in IC128335 genotype. Differential expression pattern of transcription factors of ten genes revealed that transcription factor qTaWRKY2 followed by qTaDREB, qTaEXPB23 and qTaAPEX might be utilized for developing wheat varieties resistant to drought stress. Understanding the role of TFs would be helpful to decipher the molecular mechanism involved in drought stress. Identified genotypes (IC128335 and IC36761A) may be useful as parental material for future breeding program to generate new drought-tolerant varieties.
Heat stress is one of the most limiting factors for the production of wheat. Global warming and consequent changes in climate adversely affect wheat plant growth and yield. To elucidate genetic basis and map heat tolerance traits, a set of 134 backcross inbred lines (BILs) derived from the cross between WH730/*2 HD2733 was used. The population was evaluated under late sown (LS) and very late sown (VLS) conditions, by exposing to heat stress during rabi season. Positive association of normalized difference vegetation index (NDVI), thousand grain weight (TGW), grain weight per spike (GWS), biomass and grain yield (GY) under both production conditions was observed. However, canopy temperature (CT) and days to heading (DH) showed negative correlation with GY under heat stress. A total of 9 Quantitative trait loci (QTL) were discovered on 7 chromosomes, which includes 4 QTLs in LS and 5 QTLs under VLS condition. Combining the results of these QTLs revealed a major stable QTL for DH (qDH_iari_5A) on chromosome 5A with 23% and 26% explaining phenotypic variance under both sowing conditions. QTL for NDVI was detected on chromosome 1B while QTL for SL and GY on chromosome 2A. The identified QTLs in the genomic regions could be targeted for genetic improvement and marker assisted selection for heat tolerance in wheat.
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